This is something I hear a lot: "My doctor is going to refer to me to X specialist, but they haven't called me yet to tell me when the appointment is. That was X weeks ago."
Don't wait for them! If they say they'll do it, and it's been a few days and you haven't heard anything...call them! Most likely they have a lot of patients and a lot of tasks, and they're never going to be able to prioritize your needs to the same degree you will (despite how well-intentioned they probably are). It's OK to call them and politely press the matter. See if you can make the appointment on your own, ask how you can help, when you can expect to hear from them next, etc. Be polite, but advocate for yourself.
A gap in treatment or a delay in seeing a specialist can be a bad thing, so there's nothing wrong with actively pushing to make it happen.